The article reviews key aspects of the Italian presidents' activity under A. Pertini, F. Kossiga, O.L. Scalfaro, C.A. Ciampi and G. Napolitano. Special attention is paid to the comparative analysis of Carlo Azeglio Ciampi's and Giorgio Napolitano's presidency results, as well as of external factors correlating with these politicians' ratings, considering their significant influence on the head of state institute transformation during the period of their tenures. The aim of the paper is to review the examples of initiatives taken by C.A. Ciampi and G. Napolitano, which is necessary for highlighting new trends of the presidency development in Italy. Systematization and sequencing of popular approaches in the research allow to sort out distinctive characteristics of relations among three political actors: the head of state, political parties and the government. The author conducts comparative analysis of the two presidents' tenures results. The study of C.A. Ciampi's and G. Napolitano's ratings is carried out to determine a decision-making pattern. In the article, the examples of an informal instruments usage are considered, and their effectiveness is evaluated. In this respect, it is possible to review the transformation of the role of a president as an actor responsible for the country's political system stability. Relations between the prime-minister and the head of state are the subject for a separate consideration. In this article, the system analysis method together with other universal scientific approaches (comparative historical, institutional and structural-functional) are used. The contribution of this research consists of defining the role of informal instruments in the decision-making process. Unfortunately, in Russian bibliography, only limited attention is paid to domestic policy issues of the Second Italian Republic. However, the research conducted by the author should elucidate the specificity of presidency and its relations with other public institutes. This paper is addressed to scientists devoting themselves to the South Europe political research, particularly Italy, as well as to anyone interested in the Italian domestic policy issues. Additionally, it may be used in further comparative politics investigations, for the analysis of presidential activities in other European states.